Vibratory rotary screening mechanism



March 17, 1953 N. w. JONssoN ET A-L 2,631,506

VIBRATORY ROTARY SCREENING MECHANISM Filed Oct. 29, 1946 g J j Fig.2. 9 j? 2 v 18 Its 1 Patented Mar. 17, 1953 VIBRATORY ROTARY SCREENING V V MECHANISM Nils Walfrid Jiinsson, Lidingo, and Karl Olof Lindgren,

Djursholm,

Sweden, assignors to Aktiebolaget A. Ekstroms Maskinaflar, Stockholm, Sweden, a corporation of Sweden Application October 29, 1946, Serial No. 706,320 In Sweden November 6, 1945 3 Claims.

This invention relates to vibratory rotary screen assemblies and more particularly to mountings therefor. It is particularly applicable to vibratory rotary screening apparatus of the type disclosed and described in U. S. Patent No. 2,406,618, to which reference may be made for a fuller understanding of the present invention.

In that type of vibratory screens in which the vibrating part is throughout elastically suspended, e. g., by means of helical springs, it often occurs that the vibrations are transmitted to those parts which are not intended to vibrate as well as to the foundation carrying the screen. This results in a less effective screening action due to the reduction of the relative movement between the vibrating and the non-vibrating parts.

The object of the present invention is to avoid such drawback and to secure a more effective screening action. This object is attained by also elastically mounting the non-vibrating base or frame for the vibrating screening member on springs or the like, whereby two interconnected swinging systems are obtained. Suitable selection of the constants for the springs and of the swinging masses, according to the invention, results in lower power consumption for the operation of the screen and a more effective screening action due to more favorable relative movement between the vibrating rotary screen and the non-vibrating parts.

Further advantages of the novel mounting are the reduction of stresses on the screen construction and almost no disturbance of the support ing foundation.

Two embodiments of the invention are illustrated in the accompanying drawings in which like numerals refer to like parts in both views, and in which:

Fig. 1 is a diagrammatic side elevation of one embodiment and Fig. 2 is a similar view of the other embodiment.

In the embodiment of Fig. 1, a rotary vibrating screening drum 9 is mounted on shafts I for rotation and vibration in bearings l and is driven and vibrated by any conventional drive, not shown. The screening member 9 is completely or partly immersed in a trough or vat 3 containing liquid. The bearing members [0 are resiliently mounted by means of coil springs 2 on brackets 6 aifixed to the non-vibrating vat 3 whereby the screening member 9 may vibrate freely on the springs 2, moving relative to the vat 3.

The vat 3, in turn, is mounted on a base or supporting frame 8 which is supported by coil springs 4 on an underlying foundation 5. Thus the vibrating part consists of the rotating vibrating screening member 9, disposed and arranged so as to vibrate relative to the nonvibrating vat 3, but the said vat is resiliently mounted so that two inter-connected swinging systems are obtained and there is almost no vibration transmitted to the foundation 5.

In the embodiment shown in Fig. 2 the bearings it for the screening member 9 are mounted directly on pedestals I set on the foundation 5. In both embodiments the vat 3 is mounted directly on the base 8 in order to obtain sufficient trough weight.

By taking into account the damping forces between the rotary screening drum, the vat, and the liquid in the vat, the constants for the springs and the weight of the vat may be properly proportioned. We have found that the ratio of the weight of the screen to that of the vat in which it is suspended should preferably be at most approximately 1:1.25 and may be less (e. g., 1:1.35, 1:2, etc.) in order to obtain the more favorable relative movement which is a feature of the invention. Since in existing devices (in which the vat is rigidly mounted) this weight ratio of screen to vat is generally 1:1, if it is desired to modify such existing devices to secure the advantages of the invention, in addition to spring mounting the vat, separate base plates may be rigidly attached thereto to provide the necessary additional weight to reduce this ratio to 1:125 or less. 4

In determining the elasticity and the relative masses, it is necessary to take into account the width of the slits in the screening member, which considerably influences the damping forces.

While preferred embodiments of the invention.

have been disclosed herein it will be evident that. changes can be made within the spirit and the- 3 same both with respect to each other and with respect to said foundation, the constants of said sprin mountings and the masses of said screen and vat being so chosen that two interconnected swinging systems are obtained and the ratio of the weight of said screen to that of said vat bein at most approximately 1:1.25.

2. In a screening mechanism for screening liquid suspensions and arranged to be held on a stationary foundation, the combination comprising a vat for the liquid suspension, a vibratory rotary screen arranged in said vat to be at least partially submerged in the liquid suspension therein, spring mountings resiliently supporting said vat on said foundation and other spring mountings supporting said screen on said vat, the constants of said spring mountings and the masses of said screen and vat being so chosen that two interconnected swinging systems are obtained and the ratioljof the weight of said screen to that of said Vat being at most approximately 1 1.25.

3. In a screening mechanism for screening liquid suspensions and arranged to be held on a stationary foundation, the combination comprising a vat for the liquid suspension, a vibratory rotary screen arranged in said vat to be at least partially submerged in the liquid suspension therein, spring mountings resiliently supporting said Vat on said foundation and spring mountings independent of said first named mountings also resiliently supporting said screen on said foundation, the constants of said spring mountings and the masses of said screen and vat being so chosen that two interconnected swinging systems are obtained and the ratio of the Weight of said screen to that of said vat being at most approximately 1:1.25,

NILS WALFRID JGNSSON. KARL OLOF LIN'DGREN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,153,579 Seybold et a1 Sept. 14, 1915 1,387,238 Cave Aug. 9, 1921 1,455,907 Daman May 22, 1923 1,505,835 White Aug. 19, 1924 1,882,968 Shenck Oct. 18, 1932 2,029,818 Wettlaufer -1 Feb, 4, 1936 2,183,660 Symons Dec. 19, 1939 2,496,618 Lindgren Aug, 27, 1946 2,437,651 Rasmussen 1 Mar. 9, 1948 2,514,159 Jonsson July 4, 1950 FOREIGN PATENTS Number Country Date I 551,572 Germany June 2,1932 825,745 Germany 1.. Feb. 15, 1936 795,997 Germany May 15, 1941 

